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GH2 Cake v2.3: reliability and spanning in 720p, HBR, 24p, and VMM at 2-2.5x stock bit rates
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  • Mark_the_HarpMark_the_Harp

    This was going on outside my window one morning - the steaming trees of death!

    For ipod users it's at http://vimeo.com /38840506 (remove the gap)

    Cake 1.2 QP20 plus a bit of curves in post. Last shot ex tele mode. All 14-140 lens. I lost a bit of my tripod so couldn't use it - then found it just after all the mist went away.

  • Mark_the_HarpMark_the_Harp

    I've been using Cake for quite a while now, and had a dabble with the Sedna settings but to be honest I prefer cake and have gone back to it - for the same reason that @_gl sites, that the new settings are too hungry on card space for the cards / use I need, which is shooting 4-5 minute sequences of music. Cake seems to do what I want particularly with QP set to 20. Also it's nice to stick with a setting and get used to what it does rather than switch around constantly trying new settings (I think).

  • davidhjlindbergdavidhjlindberg

    Thank you all, really helpful information!

  • LPowellLPowell

    @_gl Good summary of the trade-offs of different patch optimization strategies. I'd also add that my research on Flow Motion confirmed one of the claims made by Intra-frame advocates:

    The image quality of P and B-frame macroblocks produced by standard AVCHD encoders is inferior to the image quality of I-frames.

    That's because the built-in Scaling Tables in standard AVCHD encoders use coarser quantizers in P and B-frames than in I-frames. To fix that problem, I customized the Scaling Tables in Flow Motion v1.11 to produce P and B-frame image quality comparable to I-frame macroblock quality. This allows Flow Motion to maintain consistent I-frame quality levels while reaping the efficiency benefits of short-GOP encoding.

  • balazerbalazer

    I am now touting the ability to choose your own quantizer setting as a feature in Cake. It was my priority from the beginning to have the rate control working properly and find the right limits for reliable operation, so that you could use any ISO and quality level that you want. I chose a quantizer setting of 22 simply because it offered a balance of file sizes and quality that made sense to me. Someone else might want higher quality and larger files, and with Cake, that's easy to do: just change the quantizer setting to 20 or 18. Below 18 you're going to be hitting the limits too frequently, and so you should look at settings with higher limits, such as bkmcwd's Gop3zilla.

  • _gl_gl

    @davidhjlindberg, see the 1st post for Cake's mission statement.

    It all depends on your exact priorities - Cake and Flow Motion try to give good quality & consistency at reasonable bitrates & with reliability (across many recording modes) & spanning. They use low-GOP and are tuned for consistent frame-quality, but as a result they are also less efficient than long-GOP and you loose a little overall image quality. My (unfinished) Sweet16 attempts shifts the balance back to that quality, but probably sacrifices reliable spanning and low-GOP-style motion in the process. If you need top image quality above all else and have a fast/large enough card, you probably want Driftwood's high-bitrate intra patches (I've never tried them myself as I can't justify the file sizes & storage/backup reqs).

  • balazerbalazer

    David, the main difference between Driftwood's intra settings and mine are that intra is less efficient than GOP3 for the same quality, and intra has better frame-to-frame consistency. He also has some higher bit rate settings that are capable of higher quality.

    Intra-frame settings have an advantage over inter-frame settings for frame-to-frame consistency, because the GH2 encoder sets I-frame quantization parameters differently from how it sets P- and B-frame QPs. P- and B-frames will use the quantizer setting that you set, while I-frames will use that setting plus or minus two. The lower the quantizer setting, the less apparent the differences. At a quantizer settings of 22, the differences are small and not usually noticeable. These differences remain even if you change the scaling tables. (which I did, to make the P-frames more closely match the I-frames, but it was hardly necessary because the default scaling tables for P-frames and I-frames are nearly identical)

  • davidhjlindbergdavidhjlindberg

    Hi folks! I've been out for a while and sees that there are new patches. Can someone make a summery of the benefits of using Cake rather than Orion?

    All I'm interested of is getting the highest quality in good light conditions.

  • duartixduartix

    Sorry, I meant the Quantizer for 1080 modes. I know about Initial Quantizer. But I've made a few preliminary retesting and it looks like it's coming from the GOP change. Stock GOPs on daylight footage honour the QP, the GOP changes I did for timelapsing are interfering with the QP, which seems odd since I'm using shutter speeds around 1/5s.

  • safarisafari

  • safarisafari

    Oh I am really liking my GH2 ...now that I am figuring out these hacks....Took this testing "Cake" V1 Description: Just a Test of the GH2 with Lumix 20mm lens in EX tele mode. Using the latest "Cake" hack. All seems satble for me....Shot in smooth mode -2 -2 -2 -2 .....I am starting to rally like this GH2...I have only had it for a week now and learning all it can do...and that is plenty!

  • _gl_gl

    @duartix, I believe the Initial Quantizer setting only affects the first second or so. It's what the camera starts with before settling into the main Q settings 'Quantizer for 1080 modes' etc.

  • duartixduartix

    Thanks @_gl !

    Strange, if I understood your comments correctly, I tried something similar (lowered Initial Quantizer, raised Frame Limit to 10M and tried GOP12). I wasn't using B-frames though. Frames were still encoded at Q23 be it 24p or HBR...

    Perhaps it's the footage I'm filming...

  • _gl_gl

    @duartix, I've attached Sweet16 v0.8. Note it hasn't had any buffer tuning, any suggestions are welcome.

    This is the transition from still -> panning -> still:

    image

    gl_Sweet16_0.8.zip
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    Sweet16._0.8_Still2Pan2Still.PNG
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  • balazerbalazer

    Duartix, I tried changing the 1080 quantizer setting in Cake 95 to 18. Some quick testing in VMM-80% and HBR mode showed that the block QPs were all 18 or below when the frame limit and bit rate limit were not met.

    Cake 1.1 and 1.2 had quite a number of settings that I'd copied without knowing what they do. I've removed those settings in Cake 95, so it's much simpler and easier to study. Whether the differences between Cake 95 and Cake 1.1 & 1.2 would affect the success of a quantizer setting below 20, I don't know.

    bkmcwd's settings are also worth checking out. Gop3zilla uses a quantizer setting of 16, and Natural uses 18. I tried HBR mode in Natural v1.11 with my 95 MB/s 32-GB card, and it was not stable. But I don't have the 64-GB card that he recommends, so I can't say if the settings would have been any more stable with a faster card.

    .

    After further testing of HBR mode in Cake 95, the reliability is looking very good. But I still believe that 24p and VMM are going to be the most reliable modes.

  • balazerbalazer

    It is impossible to show the actual time remaining, because the bit rate varies and cannot be predicted.

  • phoriaphoria

    @balazer, thanks. it would be great if it show actual time remaining display.

  • mozesmozes

    I wish i could make it more clear, sorry..
    The lens i used is a Olympus M. Zuiko Digital ED 14-150mm 1:4-5.6
    Practical all shots where done on 150mm F5.6 with tele2.
    I am indoors pointing the cam true my window, for that i use a very old Cokin polarisation filter.
    If i am not wrong, the profile was Nature -2 -2 +2 -2

    IMAG0158.jpg
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  • LPowellLPowell

    @mozes Could you be more specific in detailing the shooting setup of each case? I'm mystified as to how the same patch could produce stunted videos in one test, and healthy videos in the next...

  • mozesmozes

    @LPowel All where done with the same patch. cake95
    Only the settings in the gh2 menu are different, for example idynamic on high and off.
    High iso's and shutter speeds, and tele2 on or off.
    All with autofocus, and when the gh2 try to get in focus, while for example zooming, i change the shutter or iso, its something the gh2 doesent like.
    Normally i get then a speed error, but not this time, perhaps thats the reason.

  • balazerbalazer

    It's just a quirk of VBR settings. The time remaining display will always show less than the actual time remaining.

  • phoriaphoria

    I've just tried Cake 95 in my Sandisk 32Gb / 95mb. The image quality looks good. But during the recording, the remaining time still remain the same 37 min in 24p. even though I recorded more than 37 min. is it a bug or I made some mistake during the patch ? Thanks

  • LPowellLPowell

    @mozes I'm confused, the first pair of Stream Parser results you posted were definitely dysfunctional, and the downloaded MTS files contained numerous encoding flaws in both P and I-frames. The trio of Stream Parser results you posted later showed much healthier behavior. Were all five examples shot with the same patch?

  • duartixduartix

    @Kihlian : Moving the camera like crazy will not tax the encoder as it will most probably will cause motion blur which is easy to encode. If you want to tax the encoder use a very textured subject a high enough shutter speed and slowly rotate the camera.

    @_gl : I'd like to take a look at your Cake mod.

  • KihlianKihlian

    Tried the v95, set the quantizer to 20, spans on SanDisk HD VIDEO, like the results, moved the camera around like crazy inHBR 25p give me only btr/s under 20000!!! ExTele also works and give me 27000 kbt/s.

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